OUAGADOUGOU (Reuters) - Burkina Faso has issued an international arrest warrant for Guillaume Soro, the speaker of Ivory Coast’s parliament, on charges related to a failed coup last year, Burkinabe military sources said on Friday.

The warrant against the ex-rebel leader turned politician risks raising tensions between the two neighbouring West African nations, which share a history of close, if often fraught, economic and political ties.

Authorities based the decision to issue the warrant on an audio recording of a conversation allegedly between Soro and Djibril Bassole, a political ally of Burkina Faso’s deposed longtime ruler Blaise Compaore.

In the recording, which was posted on the Internet last year, the two men discuss ways to support the coup against Burkina Faso’s interim government led by Compaore’s former spy chief General Gilbert Diendere.

Last September’s week-long power grab by the elite Presidential Security Regiment temporarily derailed the country’s transition back to democratic rule following Compaore’s ouster.

It failed after regular army troops marched on the capital Ouagadougou.

“I confirm that the warrant was issued at the beginning of the week,” said a source within the military tribunal, who declined to be named.

Diendere and Bassole are already in custody in Burkina Faso.

“Only the government can give information on this. I am not aware of (the warrant),” Soro told Reuters.

Ivory Coast’s government spokesman was not immediately available for comment.

Burkina Faso and Ivory Coast were once part of the same French colony. Around 4 million citizens of Burkina Faso live in its wealthier southern neighbour, many of them farmers who have helped make Ivory Coast the world’s leading cocoa producer.

Soro and his New Forces rebels controlled northern Ivory Coast for eight years following a 2002 civil war and were accused by then Ivorian President Laurent Gbagbo’s allies of receiving support from Compaore. Burkina Faso denied the allegation.

The New Forces played a crucial role in Ivory Coast’s 2011 civil war, backing President Alassane Ouattara’s claim to leadership after Gbagbo refused to recognise his election defeat.

Compaore has mainly lived in Ivory Coast since he was forced to flee Burkina Faso in October 2014 by popular protests against his bid to change the constitution and extend his 27-year rule.

Burkina Faso issued a warrant for Compaore’s arrest last month. Ivorian authorities have yet to comment publicly on the case. [nL8N14A3GM]